: We have a sewer odor in the basement after my wife washes clothes. The drain traps do have water in them. Our house is 12 years old and the problem started approximately 5 years ago. The septic tank has been pumped without curing the problem. We also had the drain pipes pressurized by a plumber, but still having the same problem.

Bill, Every fixture has to be trapped. You may have a bad wax seal on the toilet.See if the washer is not syphaning the floor drain while it is draining. Make sure there is a plug in the floor drain where the clean out is. Some floor drains may not have one. If this system was pressurized then i can't think of anything else at the moment.Dale's Plumbing Service LMP